Submission #169673

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Source Code Expand

#include <iostream>
#include <cstdio>
#include <vector>
using namespace std;

int main()
{
	int N;
	vector<int> coin;
	vector<int> turn;
	vector<int> coin_buf;
	vector<bool> flag;
	double E = 0.0;
	
	cin >> N;
	coin.resize(N);
	turn.resize(N);
	flag.resize(N);
	for(int n=0; n<N; n++){
		cin >> coin[n];
	}
	
	int fact = 1;
	for(int i=1; i<=N; i++){
		fact *= i;
	}
	
	for(int NUM=0; NUM<fact; NUM++){
		coin_buf.resize(N);
		for(int i=0; i<N; i++)
			coin_buf[i] = coin[i];
		
		int BUF_NUM = NUM;
		for(int i=1; i<=N; i++){
			turn[i-1] = BUF_NUM % i;
			BUF_NUM /= i;
		}
		
		vector<int> V;
		for(int i=N-1; i>=0; i--){
			V.push_back(coin_buf[turn[i]]);
			coin_buf.erase(coin_buf.begin() + turn[i]);
		}
		
		for(int i=0; i<N; i++)
			flag[i] = true;
		
		for(int i=1; i<N; i++){
			for(int j=0; j<i; j++){
				if(V[i] % V[j] == 0)
					flag[i] = !flag[i];
			}
		}
		
		for(int i=0; i<N; i++){
			if(flag[i] == true)
				E += 1;
		}
	}
	
	printf("%.12lf\n", E/fact);
	return 0;
}

Submission Info

Judge Result